Abstract

Slow crack growth in two forms of polymethylmethacrylate (PMMA) has been studied from a fracture mechanics viewpoint. It has been found that in Perspex acrylic sheet and surgical Simplex acrylic bone cement the crack velocity, V, for each material depends upon the intensification of stress at the tip of the crack. Experimental measurements have been made of V as a function of the stress intensity factor, KI, at the crack tip, and a derived V(K) relationship has been used to predict the times-to-failure of components made from Perspex and Simplex bone cement. Direct measurements of times-to-failure for Perspex are entirely consistent with the predicted values.